“We have special agents. John was a very special agent. He was a terrific person,” said Eric Immesberger, who worked with Capano for ten years. “His two children… it’s a testament to John and his lovely wife the job they did raising their children.”

“Several of us got to the hospital very quickly. John was already gone, but I can tell you that I held his shoulder and promised him that we were going to take care of his family. And we’re going to do that,” he added.

Co-worker Mary Ellen Simmons said he was wonderful at his job and he had a wonderful heart.

“He was one of the sweetest people. He was always there for you,” she said.

A college fund is being set up to help John’s two children.

Meanwhile, the shooting has brought the issue of training front and center.

Street smarts, judgment, discretion.

Other than relying on those skills taught at the police academy and honed through experience, off-duty and retired law enforcement officers appear to have few protocols to follow when confronting a crime out of uniform, like the apparent friendly fire that left a federal agent dead on New Year’s Eve.

And when different police agencies are involved, with unfamiliar officers coming face to face and making snap decisions about life and death, the peril is greater, according to a 2010 New York state study of police-on-police shootings that called for uniform protocols across agencies.

The task force created in 2010 by then-Gov. David Paterson found ‘enormous variation” in how thoroughly departments across the country train for encounters between police officers in and out of uniform, ‘if they train at all.”

‘The multiplicity of agencies is a source of many problems in policing, but it raises particular problems when officers from one agency confront an officer out of uniform from another agency, mistaking the confronted officer for a criminal,” the report said.

Capano and McGoey both died of gunshot wounds. Capano’s wake is being held today and tomorrow. He will be buried on Friday.

“That’s why I’m angry. That’s why we are all angry. John was protecting the citizens of this great state of New York. He could have turned away. He didn’t,” said ATF Agent Joseph Anarumo.

“All I do is look at his picture and I start crying. I worked with John for 15 years, and I’m doing this for him,” said colleague Mary Ellen Simmons.

On Tuesday, a law enforcement official speaking on the condition of anonymity told The Associated Press that Capano likely was shot by a retired Nassau County police lieutenant who had been down the street at a deli and responded to the robbery along with an off-duty New York police officer. Nassau County police have not commented on details, citing the ongoing investigation.

The task force that looked at protocols for out-of-uniform or retired officers included calls for improved communication and training, as well as creating across-the-board protocols for different agencies.

Since the report came out, training of police recruits on encounters with off-duty and plainclothes officers was doubled to four hours, said Janine Kava, a spokeswoman for the state Division of Criminal Justice Services. And thousands of officers statewide have taken courses for existing officers on police-on-police encounters, she said.

She did not detail any advances in uniform protocols, and it wasn’t clear whether any such rules might have saved Capano, a 23-year ATF veteran who taught U.S. military members and local forces in Afghanistan and Iraq how to investigate explosions.

But Jon Shane, a retired Newark, N.J., police captain who is now a professor at John Jay College of Criminal Justice, said there were few protocols in place for when retired or off-duty officers should insert themselves into an active crime scene.

‘Presumably these are officers who have been trained throughout their careers on how to use a weapon properly,” he said.

When officers retire, they must apply for pistol permits, as any citizen does, Shane said. On Long Island, which has been a bedroom community for New York City police officers since the 1950s, more than 17,000 pistol permits of the 66,000 issued are in the hands of retired officers.

The task force noted that although rare (police-on-police shootings have averaged one a year in the United States for the past three decades), many involve instances of white officers shooting blacks out of uniform. In the New Year’s Eve case, both victims were white.

The shooting also appears to be the second friendly fire incident in Nassau County in the last year. A Nassau police officer in plainclothes was shot to death in March by a transit authority officer in Massapequa Park.

James Carver, president of the Nassau County Patrolman’s Benevolent Association, noted significant differences in the two cases.

In March, uniformed officers were already at a domestic disturbance and had secured the situation when someone in the crowd of bystanders, possibly a retired police officer, saw what turned out to be an armed Nassau County officer in street clothes approaching the scene and yelled “Gun!”

A transit authority officer who was patrolling a nearby train station opened fire, killing the Nassau officer instantly. Lt. Kevin Smith, a Nassau police spokesman, said no public report was issued after the shooting and training issues were handled administratively.

In Saturday’s case, no uniformed officers had arrived by the time Capano or the off-duty and retired officers became involved, Carver said. The ATF agent may have been mistaken for a robbery suspect.

“Every situation should be handled differently,” Carver said. “But in general, no member of the general public, including off-duty or retired officers, should get involved if they see uniformed officers on the scene. Never interject yourself into what an active duty police officer is doing.”

Neither the retired Nassau lieutenant nor the off-duty NYPD officer has commented publicly. A telephone call to the NYPD officer’s home was not returned, and a woman answering the telephone at the deli where the retired lieutenant works said no one would comment.

Capano’s family placed blame for the shooting on the robbery suspect. “We only blame one person for the whole thing, and that was the criminal,” Tony Guerriero, Capano’s brother-in-law, told Newsday. The two officers at the scene “were all there to do their job and it just played out the way it played out.”

Please leave a comment below…

(Associated Press writers Colleen Long and Verena Dobnik and AP researcher Rhonda Shafner in New York City contributed to this report. Copyright 2012 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)